Railway signaling system



April 25, 1939. e R. PFLASTERER v RAILWAY SIGNAL ING SYSTEM 4 Sheets-Sheet 1 Filed June 5, 1957 INVENTOR George 13. SIIQPQIQ HIS ATTORNEY 'April- 25, 1939.

ca. R. PFLASTERER I ,155,870 RAI WAY SIGNALING SYSTEM Filed June 5, 1937 4 Sheets-Sheet 2 INVENTOR HIS ATTORNEY April 25, 1939. G..R PFLASTERER 2,155,870

RAILWAY SIGNALING SYSTEM Filed June 5, 1937 4 Sheets-Sheet 3 INVENTOR George lasfepel? BY H15" ATTORNEY April25, 1939. GIR. PFLASTERER 2,155,870

RAILWAY SIGNALING SXSTEM Filed June 5, 1.937

4 Sheets-Sheet 4' m NTOR u sfepen.

Geoz ge HIS ATTORNEY Patented Apr. 25, 1939 UNITED STATES} PATENT OFF-ice Y The Union Switch &' Signal: Company, Swissvale, Pa., a corporation of Pennsylvania- Application June" 5, 1937, Serial No. 146,599

21' Claims.

My invention relatesto railway signaling systems of the type involving light signalswhich are approach lighted. Specifically, my invention relates to signaling of the type described wherein 5* thesign'als involved include at least two lamps and wherein the filaments of. both lamps of a signal are checked as to continuity while such lamps are extinguished as well as while such lamps are lighted. l

The apparatus provided by this invention is an improvement on the systems shown and claimed in the applications of Henry S. Young, Serial Nos. 245,716 and 245,717, filed December 14, 1938, for Railway signaling system.

I shall describe several forms of railway signaling systems embodying my invention, and shall then point out the novel features thereof in claims.

In:the accompanying drawings, Figs. 1A, 1B. 20 and 1C are diagrammatic views which, when placedend to end in the order named, illustrate one form of apparatus embodying my invention.

Fig. 2 is a diagrammatic view illustrating a modification'of a portion of the apparatus shown in a? Fig. 1A-,and'also embodying my invention.

Similar reference characters refer to similar p, 4 pa tsin each of the several views.

Referring first to Figs. 1A, 1B, and 10, the referencecharacters RI and R2 designate the rails of a stretch of 1 railway track over which trafiic normally moves in the direction indicated by the arrows. The rails RI and R2 are divided, by insulated joints 9, into a plurality of sections VW, WX, XY, and YZ. Each section is further divided, as here shown, into two subsections IT, 2T, 3T, 41, etc. Each subsection is pr0- vided with a track battery I!) connected across suitable distinguishing reference character and cach'including an upperindication. unit U anda lower indication. unit L. Each indication unit, as

here shown, is of. the type commonly known as a searchlight signal. Referring to signal l2, for example, theunits of that signal each comprise an armature 16 mounted to rotate between an inter mediate position to which it is biased, and two extreme positions. Each armature I6 is controlled by an armature winding l1, and is polarized by the field from a permanent magnet or an electromagnet (not shown) in such manner that when the Winding I! is energized, the arma= ture will rotate to its left-hand or right-handextremeposition according as winding IT is then track section is a signal each designated by asupplied-with" current of normal or reverse polarity, respectively. Attached to each armature I 6 to rotate therewith-are three colored roundels G,.R, and Y, which are arrangedto be disposed in the path of a beam of light projected from an associatedlamp UEor LE according as the armature l6 occupies its left-hand extreme position, its intermediate position, or its right-hand extremeposition, respectively. For convenience in illustration, eachlamp UE and LE in the drawings is shown disposed'above the associated roundels, but it willbe readily understood that in actual practice each lamp will be located directly back of the associated roundeland will have associated therewith a suitable optical system, not shown, for projecting a, beam of light from the lamp. Operatively connected with each armature I6 is a circuit controller comprising two movable contact fingers l8 and I9. The movable contact finger l8 cooperates with a fixed contact 20 to close a contact Iii-20 when the armature It occupies its left-hand extreme position, and with a fixed contact 21' toclose a contact l82l when the armature occupies its intermediate position or its right-hand extreme position; while the movable contact finger l9 cooperates with a fixed contact 22- to close a contact Iii-42 when the armature I occupies its right-hand extreme position, and witha-fi'xed contact 23 to close a contact l9-23 when the armature occupies its intermediate or its left-hand extreme position. A signal of the type described is disclosed and claimed in Letters Patent of the United States No. 1,864,224, granted to Wesley B. Wells, on June 21, 1932, for Light signal.

For governing the signals, each section is provided with: two line circuits each including a pair of conductors extending to the signal for the section. next in advance and each including front contacts of the associated track relays.

For governing the lamps UE and LE of the signals, each section is provided with an approach lighting relay designated by the reference character ER with a prefix the same as the reference character of the associated signal. The lamps UE andLE are controlled in such a manner as to become lightedwhenever the associated relay ER is released, and the relays ER are controlled in such a manner as to become released whenever the, section next in rear of the associated section becomes occupied.

Each s ectionis provided with a suitable source of direct current and with a suitable source of alternating current, the terminals of which are designated, by the reference characters B and C, and BX and CK, respectively.

For governing the character of the current supplied to the lamps UE and LE, each section is provided' with a power-off relay designated by the reference character P0 with a prefix the same as the reference character of the associated signal. That is, the current for the energization of the lamps UE and LE is supplied from the associated terminals BX and OK or from the associated terminals B and C according as the associated relay PO is energized or deenergized, respectively. The

relays P0 are governed in such a manner as to be energized only when the source of alternating current is present. The current for lighting the lamps, therefore, is normally supplied from the alternating current source but is automatically switched over to the direct current source when the alternating current is absent.

For governing the polarity'of the currentsupplied to the line circuits for the section next in rear, each section is provided with two pole changing relays designated by the reference characters UPC and LPG each with a prefix the same as the reference character of the associated signal.

For controlling the relays PC and the current supplied to the line circuits for the section next in rear as Well as for governing both mechanisms of the associated signal, each section is provided with an auxiliary lightout relay designated by the reference character LOP with a prefix the same as the reference character of the associated signal.

For at times controlling the relays LOP, each section is provided with two direct current lightout relays designated by the reference characters ULO and LLO- each with a prefix the same as the reference character of the associated signal. Each relay ULO and LLO is connected in series with the lamps UE and LE, respectively, of the associated signal whenever the associated approach lighting relay ER, is released. Since relays ULO and LLO are direct current relays, I have connected across the winding of relays ULO and LLO asymmetric units 24 and 24A for the purpose of by-passing each half wave of alternating current so that the relays will operate on alternating current. It will be apparent, therefore, that each relay ULO and LLO will become energized whenever the lamps UE and LE, respectively, of the associated signal are lighted either by alternating current or by direct current.

Each auxiliary relay LOP is provided with two energizing circuits. Referring to signal I4, for example, relay MLOP is normally energized by a circuit which passes from terminal B through front point of contact 25 of relay l dER, filament 26 of lamp UE of signal I4, wire 21, filament 28 of lamp LE of signal l4, front point of contact 29 of relay MER, back point of contact 30 of relay MULO, back point of contact 3| of relay LLO, and relay MLOP to terminal 0. When relays MULO and MLLO are both energized, however, relay MLOP is provided with another energizing circuit which passes from terminal 3 over front contact 32 of relay MULO, front point of contact 3! of relay I 4LLO, and relay I4LOP to terminal C. Relay MLOP, therefore, is energized only if the filaments of each lamp UE and LE are intact both when the lamps are extinguished as well as when the lamps arelighted. It is understood, of course, that the resistance of relay MLOP is of such value that the current required by this relay will not be sufiicient to Associated with each section. 15 a .1 Wa

rectifier designated by the reference character Q with a prefix the same as the reference character of the associated signal. Each rectifier Q has its input terminals connected across the lower line conductors for the associated signal and its output terminals, of course, supply energy in one direction only regardless of the direction of energization of the associated pair of line concluctors. As will be described more in detail hereinafter, the rectifiers Q are effective, at times, when the associated relay LOP is released, t6 supply energy in the reverse direction to each winding I! of the associated signal to cause both mechanisms to assume the condition for the disthe normal and reverse directions, respectively.

For example, relay HDP is energized by a circuit which includes contact l8-20 of upper unit U of signal H, and relay I2HP is energized by a circuit which includes contacts l8-2l and a 5-22 of upper unit U of signal l2. Each of the other relays DP and HP is controlled in a similar manner.

Having thus described in general the apparatus shown in Figs. 1A, 1B, and 1G, I shall now describethe operation of the system.

Each of the signals is capable of displaying the following indications: When windings I? of the upper and lower mechanisms are both deenergized (see signal 15) that signal is caused to assume a condition for the display of a red light over a red light to indicate stop when relay l5ER becomes released. The lighting circuit for lamp UE may be traced from terminal BX through front point of contact 33 of relay ISPO, relay IS'ULO and asymmetric unit 24 in 'multi ple, back point of contact 34 of relay ISER, fila-' ment 26 of lamp UE, back contact 35 of relay I BER, and front point of contact 36 of relay I5PO to terminal OK. The lighting circuit for lamp LE may be traced from terminal BX through front point of contact 33 of relay ISPO, relay I5LLO and asymmetric unit 24A in multiple, back point of contact 31 of relay I5ER, filament 28 of lamp LE, back contact 35 of relay I5ER, and front point of contact 36 of relay I5PO to terminal CX.

The lamps UE and LE for each of the other signals are provided with lighting circuits similar to those just traced for the lamps associated with signal l5.

When the upper mechanism U is energized in the reverse direction and the lower mechanism L is deenergized (see signal M), the signal is in condition to display a yellow light over a red light to indicate approach when associated lamps UE and LE become lighted.

When the upper mechanism U is energized in the reverse direction and the lower mechanism L is also energized in the reverse direction (see signal I3), the signal is in condition to display a yellow light over a yellow light to indicate approach medium when associated lamps UE and LE become lighted.

When the upper mechanism U is energized in the reverse direction and the lower mechanism L is energized in the normal direction (see signal J2), the signal is in condition to display a yellow light above a green light to indicate approach intermediate when associated lamps UE and LE become lighted.

When upper mechanism U is energized in the normal direction and lower mechanism L is deenergized (see signal II), the signal is in condition to display a green light above a red light to indicate proceed when its lamps UE and LE are lighted.

As here shown, a train K occupies the section immediately to the right of location Z so that signal I5 is in the stop condition. As a result, winding ll of upper mechanism U of signal I4 is energized in the reverse direction and winding I I of lower mechanism L of that signal is deenergized. The circuit for winding H of upper unit U may be traced over a path from terminal B at signal I5 through relay I5ER, back point of contact 40 of relay IEUPC, front contact M of relay 8TB, front contact 42 of relay 'ITR, front point of contact 53 of relay I4LOP, winding I'I. front point of contact 44 of relay I4LOP, front contact 45 of relay 'iTR, front contact 46 of relay 8TB, and back point of contact 41 of relay IEUPC to terminal C.

Since signal I4 is in condition to display the approach indication, winding I! of upper unit U of signal I3 is also energized in the reverse direction over an easily traced circuit which includes the upper line conductors of section X-Y and which is similar to the circuit just traced for winding ll of unit U of signal I4. The positioning of unit U of both signals I3 and I4 in the extreme right-hand position will cause both relays l3I-IP and IQHP to be energized over easily traced circuits similar to the circuit already traced for relay IZI-IP. Since relays IAHP and I3HP are both energized, a circuit is established for energizing winding ll of lower unit L of signal !3 in the reverse direction. which circuit may be traced over a path from terminal 13 at signal l4 through front contact 53 of relay I4LOP, front contact 5I of relay I4I-IP. back point of contact 52 of relay I4LPC, front contact 53 of relay 6TB, front contact 54 of relay 5TR, front point of contact 55 of relay I3LOP, winding I 1, front point of contact 55 of relay I3LOP, back contact 51 of relay I3DP, front contact 58 of relay I3HP, front contact 59 of relay 5TB. front contact 69 of relay GTR, and back point of contact 6| of relay MLPC to terminal C.

Since signal I3 is in condition to display the approach medium indication. relay I'3UPC will remain released but relay I3LPC and the lower line conductors for section W-X will both become energized. The circuit for relay I 3LPC may be traced over a path from terminal B through front contact 62 of relay I3LOP, contacts I8-2'I and Iii-22 of lower unit L of signal I3- and relay i3LPC to terminal C.

With the apparatus at signal l3 in this condition. winding I1 of upper unit U of signal I2 remains energized in the reverse direction over an easily traced circuit but winding I! of the lower unit L of signal I2 is energized in the normal direction. The circuit for supplying energy to winding I! of lower unit L of signal I2 may be traced over a path which passes from terminal B at signal I3 through front contact 62 of relay 53LOP, contacts I8-2I and I9-22 of lower unit L of signal 53, front point of contact 53 of relay I3LPC. front contact 64 of relay 4TB, front contact 55 of relay 3TB, front contact 66 of relay IZI-IP, back contact 6'! of relay IZDP, front point of contact 68' of relay IZLOP, winding II, front point of contact 69' of relay IZLOP; front contact I0 of relay 3TR, front contact II of relay lTR,

and front point of contact I2 of relay EBLPC to terminal C.

The normal energization of winding ll of lower I unit U of signal I2 establishes a circuit for relay I2UPC which circuit may be traced from terminal B through front contact I3 of relay IZLOP, contact I82B of lower unit L of signal i2, and relay I2PC to terminal C. When relay IZPC is energized, the winding I! of upper unit U of signal II is energized in the normal direction by a circuit which passes over a path from terminal B at signal I2 through Winding of relay IZER, front point of contact M of relay IZUPC, front contact I5 of relay 2TB, front contact I6 of relay ITR, front point of contact 11 of'relay IILOP, winding Il', front point of contact 18 of relay IILOP, front contact I9 of relay iTR, front contact 8B of relay 2TH, and front point of contact 8I of relay lZUPC to terminal C.

Signal Ii being in the proceed position, relay IIDP is energized over contact Iii-28 of upper unit U of that signal. The energization of relay HDP opens its back contact 82 so that winding 57 of lower unit L of signal I! is deenergized even though the lower line conductors are supplied with energy at signal I2. With the apparatus at signal II in this condition, relay IIUPC is energized over a circuit which passes from terminal B through front contact $3 of relay IILOP, contacts i82I and I923 of lower unit L of signal II, front contact 84 of relay IIDP, and relay I IUPC to terminal C. The energization of relay iIUPC maintains the energization in the normal direction of the upper line concluctors for the section in rear of location V so that the signal (not shown) for that section is also in condition to display the proceed indication.

The relays UPC are provided with a slow release characteristic so that tumble-down of the signal circuits to the rear will be avoided when the relays PC are transferred from one control circuit to another. For example, when the train K departs from the section immediately to the right of signal I5 so that signal I2 will be caused to assume a condition for the display of the normal proceed indication, the circuit for relay I2UPC will be momentarily opened while contacts I8 and IQ of lower unit L of signal I2 are changing their positions. Due to the slow releasing characteristic of relay IZUPC, however, front points of contacts 14 and BI of relay IZUPC will not become opened to disturb the energization of the upper line circuit to the rear.

Having thus described the operation of the signaling system, I shall now describe the lightout protection afiorded by the apparatusembodying my invention.

For example, with all apparatus in the condition shown in the drawings, I shall assume that either filament 26 or filament 28 of the lamps UE and LE, respectively, of signal l4 becomes broken so that relay I4LOP becomes released. When relay I4LOP is released, the opening of its front contact 50 will disconnect energy from the lower line conductors for section XY so that signal I3' will be caused toassume a condition for the display of the approach indication. When signal I3 assumes this condition, signal I2 will be caused to assume the condition for the display of the approach medium indication and signal I I will be caused to assume the condition for the display of the approach intermediate indication. Consequently, the open filament of either lamp UE or LE, when such filaments are dark, will cause the next three successive signals in the rear to display more restrictive indications than they would ordinarily display. An engineman approaching signal I l, therefore, would receive three restrictive indications before reaching signal I4 50 that he would have ample time to prepare to stop at the signal having the defective lamp.

The deenergization of. relay I4LOP would also connect, through rectifier MQ, windings ll of both upper and lower units of signal I I to the lower line conductors for section YZ. Since, however, these conductors are carrying no energy due to the presence of the train K in the section to the right of location Z, both windings I I would become deenergized to cause signal I4 to assume the stop condition. Another train approaching signal I4 would, therefore, receive an indication comprising a single red light.

If one of the filaments of either the lamp UE or LE at either signal II, I2, or I3 becomes opened, three successive signals tothe rear would be caused to display more restrictive indications in a manner similar to that described in connection with signal I4 and the signal at which the lamp became opened would be caused to assume a condition for the display of a single yellow light. For example, if filament 2B of lamp UE at signal I2 becomes opened, then relay IZLOP would become released. The releasing of relay IZLOP would disconnect windings I! of both upper and lower units of signal l2 from their usual control circuits and would connect both windings Il' through other circuits including rectifier IZQ to the lower line conductors for section WX. Although the line conductors are supplied with energy in the normal direction, the rectifier IZQ is so poled that the energy supplied to windings I7 is in the reverse direction. The circuit for winding I! of upper unit U of signal l2 passes from the output terminals of rectifier IZQ through back points of contacts 8'5 and 86 of relay IZLOP and the circuit for winding I! of lower unit L of signal I2 passes from the output terminals of rectifier I2Q through back points of contacts 68 and 69 of relay I2LOP. Signal I2, therefore, would be in condition to display a single yellow light to an approaching train. It is understood that the same operation would take place if the filament 28 of the lower lamp LE should become opened instead of the filament 26 of lamp UE. Also, each of the signals l3 and II and associated apparatus would function in a similar manner if the filament of either lamp associated therewith became opened. For example, if filament 26 of lamp UE of signal I l becomes opened so that relay ILOP becomes released, then winding ll of lower unit L of signal I2 would become energized in the reverse direction by a circuit which passes from the output terminals of rectifier I IQ through back points of contacts 94 and 95 of relay IILOP. The circuit for supplying energy to rectifier HQ passes from terminal B at signal [2 through front contact I3 of relay IZLOP, front contact 87 of relay IZHP, back point of contact 88 of relay I2LPC, front contact 89 of relay ZTR, front contact 90 of relay ITR, rectifier HQ, front contact 9i of relay I'IR, front contact 92 of relay 2TB, and back point of contact 93 of relay I2LPC to terminal C. When winding I! of unit L of sig nal II is energized in the reverse direction, that signal, of course, is in condition to display a single yellow light when relay I IER becomes released by an approaching train.

It will be noted that the lower line conductors for the section immediately in the rear of location V are supplied with energy over a circuit which includes front contact 83 of relay IILOP and front contact 96 of relay II DP. This is done to provide energy for the control of the indication units associated with the signal for such rear section (in a manner similar to that described for signal II) if the filament of one of the lamps of such rear signal should become opened.

Referring next to Fig. 2, I have illustrated herein a single signal and associated apparatus, a plurality of which when connected in a signaling system, will provide four-block, five-indication signaling similar to that just described for the apparatus shown in Figs. 1A, 1B, and 1C. That is, if a plurality of signals and associated apparatus similar to that shown in Fig. 2 are embodied in a system with wires I00, Il, I02, and I03 at the left of Fig. 2 connected to wires I64, I05, I06, and I0! at the right of Fig. 2, the system formed thereby will provide four-block, five-indication signaling. The principal difference between the arrangement shown in Fig. 2 and that shown in the preceding figures is that the normal proceed indication is a green light over a green light and the approach intermediate indication is a green over a yellow light. Otherwise, the apparatus shown in Fig. 2 functions in a manner similar to that described for the apparatus shown in Figs. 1A, 1B, and 10.

If either filament 26 or 28 of lamp US or LE, respectively, becomes opened, relay LOP, of course, will be released. The opening of front contact 598 of relay LOP will release relay UPC so that current will be supplied in the reverse direction to wires I00 and IM and will disconnect energy from wires I02 and I03. Therefore, if either filament becomes opened, the signal (not shown) for the section next in rear will be caused to assume the condition for the display of a yellow over a red light to indicate approach medium.

Also the opening of front points of contacts H0, III, H2, and N3 of relay LOP and the closing of back points of these contacts will connect windings ll of both upper and lower units U and L to line conductors I06 and I0? through rectifier Q so that both windings will be energized in the reverse direction. The signal, therefore, Will be in condition to display a single yellow light to an approaching train regardless of which lamp of the signal is opened.

From the foregoing description of each of the forms of apparatus embodying my invention, it will be seen that I have shown and described herein, lightout protection schemes as applied to four-block, five-indication signaling systems wherein if a lamp filament becomes opened, the next three signals in the rear will be caused to assume a condition, if not already in such condition, for the display of a restrictive indication, and wherein the signal at which the lamp became opened will be caused to assume a condition for the display of a single yellow light or a single red light depending upon trafiic conditions in advance.

Although I have herein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus-described my invention, vwhat I claim is:

- 1. In combination, a section of railway track, a signal for said section including two indication units, said units each comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, meansior lighting both lamps to cause the display of an indication, means governing said two mechanisms in such a manner that the signal is caused to assume a condition for displaying the. stop, approach, approach medium, approach intermediate, or proceed indication in accordance with trafi'lc conditions in advance of the signal, and means effective if the filament of either lamp becomes opened at any time to condition said mechanism for the display of one or another of two distinctive aspects according as the governing means for. said signal is then in condition to cause the signal to display the first two or the last three of said indications respectively.

2. In combination, a section of railway track, a signal'for said section including two indication units, said units each comprising a'mechanism and a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps to cause the display of an indication, means governing said two mechanisms in such a manner that the signal is caused to assume a condition for displaying a stop indication or a proceed in dication in accordance with trafiic conditions in advance of said signal, and means effective if the filament of either lamp becomes opened at any time to condition said signal for the display of :one or another of two distinctive aspects according as the governing means for said signal is then in condition to cause the signal to display the stop orthe proceed indication respectively.

3. In combination, a section of railway track,- a signal for said section including two indication units, said units each comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps to cause the display or" an indication, means governing said two mechanisms in such-a manner that the signalis caused to assume a condition for displaying a more restrictive indication or a less restrictive indication in accordance With-- traific conditions in advance of said signal, and means effective if the filament of either lamp becomes opened at any time to condition said signal for the display of one or' another of two distinctive aspects according as the governing means for said signal is then in condition to cause the signal to display the more restrictive or the less restrictive indication respectively.

4. In combination, a section of railway track, a signal for said section including two indication units, said units each comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps to cause the display of an indication, means governing said two mechanisms in such a manner that the signal is caused to assume a condition for displaying a more restrictive indication or a'less restrictive indication in accordance with trafiic conditions in advance of said signal, and means effective if the filament of either lamp becomes opened at any time to condition said signal for the display of one or the other of two distinctive indication respectively, said two. distinctive .as- I pects being also more and less restrictive respectively.

'5. In combination, a section of railway track, a signal for said section including two indication units, each said unit comprising a mechanism and .a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps-to cause said signal to display an indication, a relay, means for energizing said relay at all times provided the filament of each lamp is intact, and means including said relay and operative on deenergization of said relay for controlling said two mechanisms in accordance with trafiic conditions in advance of said signal.

6. In combination,a section of railway track, a signal for said section including two indication units, each said unit comprising a mechanism and a lamp cooperating therewith to pro-- vide a plurality of indications, means for at times supplying current to the filaments of said lamps to thereby light both lamps to cause said signal to display an indication, a relay, means for energizing said relay provided the filament of each lamp is intact, the means for energizing said relay being rendered ineffective immediately upon failure of the filament of either lamp either at a time when the lamps are supplied with current or when they are not sup-plied with current, whereby the relay becomes released at once on failure of the filament of either lamp, a circuit including a front contact of said relay for governing one of said mechanisms, and a circuit also includin a front contact of said relay for governing the other mechanism.

7. In combination, a section of railway track, a signal for said section including two indication units, each said unit comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps to cause said signal to display an indication, a relay, means for energizing said relay at all times provided the filament of each lamp is intact, means effective when said relay is energized to govern both said mechanisms in accordance with traflic conditions in advance, and other means effective when said relay is deenergized to also govern said mechanisms in accordance with trafiic conditions in advance.

8. In combination, a section of railway track, a signal for said section including two indication units, each. said unit comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, means comprising circuits for supplying current for lighting both lamps to cause said signal to display an indication, a first lightout relay connected in series with one of said lamps when the circuit associated therewith is conditioned to supply current to that lamp, a second lightout relay connected in series with the other of said lamps when the circuit associated therewith is conditioned to supply current to that lamp, an auxiliary relay, a circuit for said auxiliary relay including the filaments of both lamps in series and a back contact of each of said lightout relays when the lamps are extinguished, another circuit for said auxiliary relay including a front contact of each of said lightout relays, and means governed by said auxiliary relay for governing said two mecha- 9. In combination, a section of railway track, a signal for said section including two indication units, each such unit including a mechanism responsive to' the polarity of the current supplied theretoand' a lamp cooperating therewith to provide a plurality of indications, means for supplying each mechanism with current in one direction or the other in accordance with traffic conditions in advance of said section, means for lighting both lamps to cause the signal to display an indication, and means efiective if the filament of either lamp becomes opened at any time to cause both mechanisms to assume the same condition, the condition which the said mechanisms are caused to assume being controlled in accordance with trafiic conditions in advance.

10. In combination, a section of railway track, a signal for said section including two indication units, each such unit comprising a mechanism responsive to the polarity of the current supplied thereto and a lamp cooperating therewith to provide a plurality of indications, means. for lighting both lamps to cause the signal to display an indication, a pair of line conductors for supplying energy to one of said units, another pair of line conductors for supplying energy to the other of said units, pole changing means for reversibly supplying energy to each pair of conductors in accordance with trafi'ic conditions in advance of said section, and means effective if the filament of the lamp associated with either unit is broken to render said pole changing means inefiective and to cause each mechanism to assume the same condition.

11. In combination, a section of railway track, a signal for said section including two indication units, each such unit comprising a mechanism responsive to the polarity of the current supplied thereto and a lamp cooperating therewith to provide a plurality of indications,--means for lighting both lamps to cause the signal to display an indication, a relay, means for energizing said relay only if the filament of each lamp is intact at all times, means including a pair of line conductors for reversibly governing one of said mechanisms, means including another pair of line conductors for reversibly governing the other of said mechanisms, means including front contacts of said relay for at times connecting each mechanism to its line conductors, and means including a rectifier and back contacts of said relay for at other times connecting both units to one of said pair of conductors.

12. In combination, a section of railway track, a signal for said section including two indication units, each such unit comprising a mechanism responsive to the polarity of the current supplied thereto and a lamp cooperating therewith to provide a plurality of indications, means for lighting both lamps to cause the signal to display an indication, a relay, means for energizing said relay efiective only if the filament of each lamp is intact while extinguished as well as while buming, means including a pair of line conductors for reversibly governing one of said mechanisms provided said relay is energized, means including another pair of line conductors for reversibly governing the other of said mechanisms provided said relay is energized, a rectifier having its input terminals connected across one pair of said conductors, means including a pair of back contacts of said relay for connecting the output terminals of said rectifier to one of said mechanisms, and means including another pair of back contacts of said relay for also connecting the output terminals of said rectifier to the other mechanism.

13. In combination, a plurality of successive sections of railway track, a signal for each section each including two indication units, each said unit comprising a mechanism responsive to the polarity of the current supplied thereto and a lamp cooperating therewith to provide a plurality of indications, means for at times supplying current to the filaments of said lamps to thereby light said lamps, two pairs of conductors for each section, one pair for supplying current to one mechanism of the associated signal and the other pair for supplying current to the other mechanism of the associated signal, a relay for each section, means for energizing said relay efiective only if the filament of each lamp of the associated signal is intact, the means for energizing said relay being rendered ineffective immediately upon failure of the filament of either lamp either at a time when the lamps are supplied with current or when they are not supplied with current, whereby the relay becomes released at once on failure of the filament of either lamp, means including said relay for connecting said mechanisms to the associated pair of conductors, and pole changing means for each section governed by the associated relay and by the mechanism of the associated signal for governing the supply of current to the conductors for the section next in rear.

14. In combination, a plurality of successive sections of railway track each provided with a track circuit including a track relay, a signal for each section including two indication units, each said unit comprising a mechanism responsive to the polarity of the current supplied thereto and a. lamp cooperating therewith to provide a plurality of indications, means for each section for lighting both lamps of the associated signal to cause such signal to display an indication, four conductors for each section governed by the associated track relay, one pair for supplying current to one mechanism of the associated signal and the other pair for supplying current to the other mechanism of the associated signal, and means for each section governed by both of the mechanisms associated with the signal for such section for reversibly supplying current to at least one pair of line conductors for the section next in rear.

15. In combination, a plurality of successive sections of railway track each provided with a track circuit including a track relay, a signal for each section including two indication units, each said unit comprising a mechanism responsive to the polarity of the current suppliied thereto and a lamp cooperating therewith to provide a plurality of indications, means for each section for lighting both lamps of the associated signal to cause such signal to display an indication, four conductors for each section governed by the associated track relay, one pair for supplying current to one mechanism of the associated signal and the other pair for supplying current to the other mechanism of the associated signal, two pole changing relays for each section for reversibly governing the supply of current to each pair of line conductors for the section next in rear, and means governed by both of the mechanisms associated with the signal for each section for controlling at least one of said pole changing relays associated With said signal.

16. In combination, a plurality of successive sections of railway track, a signal for each section including two indication units, each said unit comprising a mechanism responsive to the polarity of the current supplied thereto and a lamp cooperating therewith to provide a plurality of indications, means for each section for lighting both lamps of the associated signal to cause that signal to display an indication, means for each section for reversibly governing the mechanisms of the associated signal in accordance with trafiic conditions in advance, and means for each section effective if the filament of either lamp of the associated signal becomes opened at any time to condition both mechanisms of the associated signal for the display of the same restrictive indication, the condition which the said mechanisms are caused to assume being controlled in accordance with trafific conditions in advance.

17. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section including two indication units, each of said units comprising a lamp and a mechanism associated therewith, each of said mechanisms being movable to a plurality of positions to provide a plurality of indications, means for lighting both of said lamps, circuits controlled by the mechanisms associated with each signal in accordance with their position for selectively controlling the mechanisms of the adjacent signal in the rear, a relay associated with each signal and controlling the connection of the mechanisms at such signal with the circuits leading from the adjacent signal in advance, said relay being operative when deenergized to effect the connection of the associated mechanisms with said circuits to cause said mechanisms to be controlled in one manner in accordance with the positions of the mechanisms of the adjacent signal in advance, said relay being operative when deenergized to effect the connection of the associated mechanisms with said circuits to cause said mechanisms to be controlled in a difierent manner in accordance with the positions of the mechanisms of the adjacent signal in advance, and means for energizing said relay at all times provided the filament of each lamp at said signal is intact.

18. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section including two indication units, each of said units comprising a lamp and a mechanism associated therewith, said mechanism being movable to a plurality of positions to provide a plurality of indications, a supply circuit through which current may be supplied to the filaments of said lamps in parallel to light said lamps, a relay, means controlled by said relay and operative when said relay is energized for controlling said two mechanisms in accordance with traffic conditions in advance of said signal, means for supplying current to said supply circuit and for also interrupting the supply of current to said circuit, said means being operative when conditioned to interrupt the supply of current to said supply circuit to establish a circuit including the filaments of said lamps in series through which current may be supplied to said relay, and means operative on the supply of current to said supply circuit for also supplying current to said relay.

19. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section, each of said sections having two pairs of line conductors associated therewith and extending to the adjacent signal in advance, the signal for each section including two indication units, each of said units comprising a lamp and a mechanism associated therewith, said mechanism being movable to a plurality of positions in accordance with the polarity of current supplied thereto to provide a plurality of indications, means for lighting both of said lamps, circuits controlled by the mechanisms associated with each signal in accordance with their positions for selectively controlling the supply of current and the polarity of the current supplied to the line conductors associated with the adjacent signal in the rear, a relay associated with each signal and controlling the connection of the mechanisms at such signal with the line conductors extending from the adjacent signal in advance, an asymmetric unit associated with said relay and. being operative to supply current of one polarity from one of said pair of line conductors when said line conductors are energized, said relay being operative when deenergized to establish connection from said asymmetric unit to the mechanism of one of said units, and means for energizing said relay at all times provided the filament of each lamp remains intact.

20. In combination, a stretch of railway track divided into a plurality of successive block sections, a signal for each section, each of said sections having two pairs of line conductors associated therewith and extending to the adjacent signal in advance, the signal for each section including two indication units, each of said units comprising a lamp and a mechanism associated therewith, said mechanism being movable to a plurality of positions in accordance with the polarity of current supplied thereto to provide a plurality of indications, means for lighting both of said lamps, circuits controlled by the mechanisms associated with each signal in accordance with their positions for selectively controlling the supply of current and the polarity of the current supplied to the line conductors associated with the adjacent signal in the rear, a relay associated with each signal and controlling the connection of the mechanisms at such signal with the line conductors extending from the adjacent signal in advance, an asymmetric unit associated with said relay and being operative to supply current o-f one polarity from one of said pair of line conductors when said line conductors are energized, said relay being operative when deenergized to establish connection from said asymmetric unit to the mechanisms of both of said units, and means for energizing said relay at all times provided the filament of each lamp remains intact.

21. In combination, a section of railway track divided into a plurality of successive block sections, a signal for each section including two indication units, each of said units comprising a mechanism and a lamp cooperating therewith to provide a plurality of indications, each signal having associated therewith means for at times supplying current to the filaments of said lamps to thereby light both lamps to cause said signal to display an indication, each signal also having associated therewith a relay, a circuit for energizing said relay at a time when current is not supplied to illuminate the filaments of the said lamps, another circuit for energizing said relay at a time when current is supplied to illuminate the filaments of the said lamps, said circuits being effective to energize said relay only if the filaments of both lamps are intact, and means including said relay and operative on deenergization of said relay for controlling the mechanisms of the associated signal in accordance with traflic conditions in advance of the section with which the signal is associated.

' GEORGE E. PFLASTERER.

. CERTIFICATE OF coRREcTIofl. Patent No. 2,155,870. April 25, 19 9.

GEORGE R. PFLASI'ERER.

It is hereby certified that error appears in' the printed specification of the above numbered patent requiring correction as follows: Page 7-, first column, line 28-29, claim 17, for the ,word "deenergi zed" read energized and that the said Letters Patent should be readfiith this correction therein that the same inay conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of Jnly, A. D. 1959.

Hem-3 Van Ar-sdale (seal) Acting Commissioner of Patents. 

